New lithostratigraphical, sedimentological, mineralogical and palaeontological data on the Mesozoic of Belgian Lorraine: a progress report

A multidisciplinary study of some extensively cored boreholes together with the new 1/25,000 geological mapping of Wallonia led us to propose a new lithostratigraphic canvas for Belgian Lorraine. This area is located on the N-E border of the Paris Basin, south of the Ardennes; the studied stratigraphic interval covers the Keuper to the Toarcian. Each of the new lithostratigraphic units is interpreted by macroscopic and microscopic sedimentological observations. Detailed palynological and claystratigraphical analyses were also performed, providing additional stratigraphical, palaeoecological and sedimentological data. The Habay Formation (conglomerates and red mudstones) is a fluvial unit, with immature channel conglomerates and paleosoils. The Attert Formation (dolomitic marls with gypsum and pseudomorphs) exhibits an evaporitic trend. The Mortinsart Formation (sands and marls) corresponds to a restricted marine unit, evolving towards an alluvial plain (Levallois Member). The second cycle begins with the Jamoigne Formation (bioturbated marls and limestones), a marine subtidal restricted unit, evolving towards a more sandy series (Metzert Member). The base of the third cycle corresponds to the rest of the Luxembourg Formation, composed by a superposition of sand waves. The Ethe Formation (laminar mudstones and marls) marks a deepening of the basin and the outset of marine dysaerobic conditions. The Aubange Formation (bioturbated marls with sandstones and limestones) is characterized by the reappearance of a normal benthic fauna. The Grandcourt Formation (laminar mudstones and marls) marks a return to open marine dysaerobic conditions. The Mont-Saint-Martin Formation (marls, sandy marls and oolitic ironstone) is a highly regressive unit, while the Longwy Formation (limestones) marks the initiation of a carbonate platform.